THE  MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK, 


PROGRESS  OF  THE  CITY  TUNNEL  OF  THE 
CATSKILL  AQUEDUCT 

By  Walter  E.  Spear,  M.  M.  E.  N.  Y. 


WITH  DISCUSSION  BY 

SIDNEY  W.  HOAG,  Jr.,  SAMUEL  C.  THOMPSON,  WILLIAM  F.  LAASE, 
LAZARUS  WHITE,  BERTRAND  H.  WAIT  AND 
HERBERT  M.  HALE. 


Reprint  from  Proceedings,  1012 


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SEYMOUR  DURST 


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THE  MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK 


PROGRESS  OF  THE  CITY  TUNNEL  OF  THE 
CATSKILL  AQUEDUCT 

By  Walter  E.  Spear,  M.  M.  E.  N.  Y. 


WITH  DISCUSSION  BY 

SIDNEY  W.  HOAG,  JrM  SAMUEL  C.  THOMPSON,  WILLIAM  F.  LAASE, 
LAZARUS  WHITE,  BERTRAND  H.  WAIT  AND 
HERBERT  M.  HALE. 


Reprint  from  Proceedings,  1012 


THE  MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK. 


Paper  No.  72. 

Presented  April  24tii,  1912. 


BGRESS  OF  THE  CITY  TUNNEL  OF  THE 
CATSKILL  AQUEDUCT. 

By  Walter  E.  Spear,  M.  M.  K.  N.  Y  * 


With   DISCUSSION  by 
Sidney  W.  Eoag,  Jr.,  Samuel  0.  Thompson,  William  F.  Laasb, 
Lazari  a  White,  Bertrand  H.  Wait  and 
Herbert  M.  Bale. 


After  months  of  surveys  and  studies  by  the  Board  of  Water 
Supply,  and  after  successfully  undergoing  a  careful  examination 
by  the  Board  of  Estimate  and  Apportionment,  the  City  Tunnel, 
the  last  important  link  in  the  Catskill  Aqueduct,  was  finally 
authorized  and  place*  1  under  contract  last  year,  and  the  work  i9 
now  well  under  way.  The  City  Tunnel  was  not  included  in  the 
original  plan  for  the  delivery  of  the  Catskill  supply  prepared  in 
1905  by  the  Board  of  Water  Supply;  this  plan  was  of  necessity 
submitted  before  the  problem  of  the  type  and  location  of  the  Catskill 
Aqueduct  within  the  City  could  be  properly  studied,  and  provided 
south  of  Hill  View  Reservoir  only  a  single  pipe  line  for  the  supply 
of  Brooklyn,  Queens  and  Richmond  Boroughs,  the  portions  of  the 
City  then  most  in  need.  Upon  investigation  it  soon  became  appar- 
ent that  the  tentative  plan  must  be  materially  modified  within  the 
City  limits  in  order  to  economically  provide  for  the  delivery  of 
the  entire  Catskill  supply  to  all  portions  of  the  City.  Before  re- 
questing a  modification  of  the  original  plan,  the  water  supply  needs 
of  the  City  and  the  existing  distribution  system  were  carefully 
studied.    The  good  part  of  a  year  was  spent  in  making  surveys  and 


*  Department  Engineer.  Board  of  Water  Supply. 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  63 

borings  in  the  City  to  determine  the  feasibility  of  the  tunnel  por- 
tion of  the  project,  and  during  the  interval  between  the  application 
for  the  modification  and  the  final  approval  of  the  plan,  the  boring 
work  was  continued  to  definitely  fix  the  exact  alignment  and  grade 
of  the  tunnel.  The  entire  City  Aqueduct  project,  of  which  the  City 
Tunnel  represents  the  major  part,  including  the  proposed  trunk 
mains  to  be  laid  in  the  streets  from  the  terminal  shafts  of  the 
tunnel  in  Brooklyn  to  the  Boroughs  of  Queens  and  Richmond,  was 
passed  upon  favorably  by  the  Board  of  Estimate  and  Apportionment 
of  two  administrations,  once  on  December  '10,  1909,  and  again  on 
July  1,  1910,  and  wTas  finally  approved  by  the  State  Water  Supply 
Commission  on  October  20,  1910. 

The  City  Aqueduct  plan  thus  approved  provided  for  a  pressure 
tunnel,  entirely  in  the  solid  bed  rock  underlying  the  City,  on  a 
line  nearly  18  miles  in  length  which  passes  through  the  center  of 
the  Bronx  and  Manhattan  Boroughs  and  across  the  East  River  to 
the  downtown  business  section  of  Brooklyn  Borough.  Much  knowl- 
edge of  the  geology  of  this  locality  was  gained  in  the  preliminary 
work  on  the  City  Tunnel,  which,  with  other  information,  was  pre- 
sented to  this  Society  in  February  of  last  year  in  an  interesting 
paper  on  the  geology  of  New  York  City  by  Dr.  Charles  P.  Berkey, 
the  Consulting  Geologist  on  the  City  Tunnel  project,  and  Mr.  John 
R.  Healy,  Assistant  Engineer,  Board  of  Water  Supply. 

Location  of  City  Aqueduct. 

It  will  be  noted  that  the  line  of  the  City  Tunnel,  as  indicated 
on  Plate  29  begins  at  the  southerly  end  of  Hill  View  Reservoir, 
now  under  construction  between  Jerome  and  Mt.  Vernon  Avenues 
in  the  City  of  Yonkers,  and  follows  in  a  general  way  the  highest 
ground  through  the  Boroughs  of  Bronx  and  Manhattan.  In  the 
Bronx  the  tunnel  is  being  driven  within  the  ridge  of  hard  gneiss  of 
the  Yonkers  and  Fordham  series,  lying  between  the  valley  of  the 
Bronx  River  and  that  of  Tibbet's  Brook,  following  a  location  from 
Jerome  Park  Reservoir  to  the  Harlem  River  close  to  that  of  the 
Old  Croton  Aqueduct,  and  crosses  under  Harlem  River  in  the  In- 
wood  limestone,  just  south  of  High  Bridge.  After  passing  under 
the  Harlem  River  the  tunnel  enters  the  Manhattan  schist  formation 
and  is  laid  out  under  the  easterly  escarpment  of  the  high  ground 


6  1  PROGRESS  OF  CITY  TUNNEL  OF  CATSKIEL  AQUEDUCT. 


on  the  upper  west  side  of  Manhattan,  beneath  High  Bridge,  St. 
Nicholas  and  Morningside  Parks  and  the  connecting  streets,  to  Cen- 
tral Park  at  106th  Street  and  Eighth  Avenue;  thence  under  Central 
Park,  Sixtli  Avenue.  Broadway,  Fourth  Avenue  and  the  Bowery 
to  Delancey  Street,  still  in  the  Manhattan  schist.  In  Delancey 
Street  near  the  Bowery  the  tunnel  leaves  the  schist  and  passes  be- 
neath the  streets  of  the  lower  East  Side,  to  the  East  River  near  the 
foot  of  Clinton  Street  in  a  somewhat  complicated  formation  of 
Inwood  limestone  and  Eordham  gneiss.  Before  reaching  the  East 
River  the  tunnel  enters  a  grano-diorite  intrusion  in  the  Fordham 
series  and  in  this  formation  crosses  under  the  Fast  River  to  Bridge 
Street,  Brooklyn;  thence  beneath  Bridge  Street  and  Flatbush 
Avenue  to  a  terminus  at  Third  Avenue  and  Schermerhorn  Street. 
From  the  main  line  in  Flatbush  Avenue,  a  branch  tunnel  is  to  be 
driven  through  Lafayette  Street  to  another  terminal  shaft  in  Fort 
Greene  Park. 

The  somewhat  irregular  course  of  the  tunnel  in  some  portions 
of  the  City,  notably  on  the  lower  East  Side,  is  the  result  of  the 
policy  of  locating  the  line  beneath  public  streets  and  parks  and 
avoiding  as  far  as  possible  the  expense  of  acquiring  easements  under 
private  property.  Of  the  93  870  ft.  of  the  City  Tunnel,  only  722 
ft.,  or  three-fourths  of  1%  of  the  entire  line,  is  under  private  prop- 
erty where  easements  have  had  to  be  purchased,  and  out  of  the  24 
shafts,  only  4  had  to  be  located  on  private  lands.  A  straight  line 
for  the  tunnel  in  many  localities  would  have  offered  some  economy 
in  construction,  but  the  experience  in  acquiring  the  easements  for 
the  pressure  tunnel  of  the  new  Croton  Aqueduct  indicated  that  this 
economy  would  have  been  offset  many  times  by  the  cost  of  acquiring 
rights  under  private  lands.  Furthermore,  a  tunnel  in  the  rock  under 
private  property  would  always  be  exposed  to  injury  from  drill  holes 
for  elevator  wells  and  other  purposes  made  by  persons  ignorant  of 
the  location  of  the  tunnel. 

Depth  of  Tunnel. 

As  may  be  seen  in  Plate  29,  throughout  the  Borough  of  the  Bronx 
and  in  Manhattan  from  Morningside  Park  to  the  Bowery,  where 
sound  rock  is  found  at  or  near  the  surface,  the  grade  of  the  tunnel 
has  been  fixed  at  a  depth  of  200  to  300  ft.,  which  is  from  50  to  200 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT. 


05 


66         PB0GBB8S  OF  I  ITV  TUNNEL  OF  CATS  KILL  AQUEDUCT. 


ft.  below  sea  level;  and  the  southerly  portion  of  the  tunnel  in  Brook- 
lyn has  a  depth  of  but  little  more  than  :>00  ft.  below  the  surface. 

At  intermediate  sections  the  tunnel  has,  however,  been  placed 
at  a  much  greater  depth  to  secure  everywhere  a  minimum  cover  of 
150  ft.  of  sound  rock  over  the  tunnel,  this  depth  being  considered 
necessary  to  insure  finding  a  sound,  tight  rock  in  which  to  build  the 
tunnel.  The  first  depression  made  in  the  grade  of  the  tunnel  to 
reach  sound  rock  is  in  the  section  from  the  Harlem  River  to  Morn- 
ingside  Park.  The  erosion  and  decay  of  the  limestone  in  the  Har- 
lem River  made  it  necessary  there  to  go  to  a  depth  of  330  ft.  below 
sea  level,  and  an  equal  depth  was  found  to  be  required  in  the  neigh- 
borhood of  125th  Street,  where  the  roek  floor  is  over  200  ft.  below 
the  surface  in  a  valley  in  the  bed  rock,  which  is  believed  to  repre- 
sent faulting  of  the  schist  at  this  point  and  subsequent  disintegra- 
tion and  erosion.  Another  and  deeper  depression  of  the  tunnel  line 
was  provided  at  the  southerly  end  of  Manhattan  Island  to  carry  the 
tunnel  at  a  safe  depth  in  the  solid  rock  through  the  lower  East  Side, 
where  in  Hester  and  Clinton  Streets  the  borings  showed  that  the 
rock  is  more  or  less  decayed  to  a  depth  of  400  to  500  ft.  Under 
the  East  River  the  bed  rock  is  found  at  a  depth  of  only  80  to  90  ft. 
below  the  surface,  but  slopes  off  rapidly  in  Brooklyn  to  the  south  and 
east.  The  depth  of  the  rock  in  Brooklyn  fixed  the  distance  in  these 
directions  to  which  the  tunnel  could  be  built;  the  depth  of  wet 
ground  at  the  end  of  the  main  tunnel  at  Flatbush  Avenue  and 
Schermerhorn  Street,  which  was  106  ft.,  represents  about  the  lim- 
iting distance  through  which  it  is  possible  to  sink  a  pneumatic 

caisson.  ■  • 

General  Description  of  Tunnel. 

The  plan  for  a  pressure  tunnel  in  the  rock  under  the  City  for 
the  delivery  of  the  Catskill  supply  was  adopted  because  this  type  of 
construction  was  found  to  be  much  cheaper  than  steel  or  cast-iron 
mains  of  equivalent  capacity;  because  the  tunnel  promised  little 
or  no  disturbance  in  the  highways  and  no  interference  with  other 
uses  of  the  streets;  and  because  the  tunnel  offered  greater  certainty 
of  an  uninterrupted  supply  of  water  at  ample  pressures  in  the  center 
of  the  City's  population. 

Of  the  24  shafts  in  the  City,  spaced  on  an  average  about  4  000 
ft.  apart,  22  shafts  will  be  completed  as  waterways  through  which 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  67 


Plate  39.— Fig.  1. 


Pi  ate  30.- Fig.  2 


68        PB0GBE8S  OF  CITY  TLNM.L  oi  0AT8KILX  AQUEDUCT. 

the  entire  Catskill  supply  of  500  million  gallons  per  day  may  be 
delivered,  by  means  of  suitable  connections,  to  the  City's  distribution 
mains;  one,  Shaft  11  in  Morningsido  Park,  will  be  a  drainage  -hail 
without  a  waterway;  and  another,  Shaft  1  in  Van  Cortlandt  Park, 
is  a  construction  shaft  and  will  he  plugged  and  refilled  on  the  com- 
pletion of  the  tunnel.  Of  the  22  waterway  shafts,  the  two  terminal 
shafts  in  Brooklyn,  Shafts  23  and  24,  will  serve  largely  to  supply 
the  trunk  mains  66  in.  and  48  in.  in  size,  which  are  being  laid  by 
the  Board  of  Water  Supply  from  these  shafts  to  the  Boroughs  of 
Brooklyn,  Queens  and  Richmond  and  two  shafts,  Shaft  3,  at  Jerome 
Park  Reservoir,  and  Shaft  10  at  135th  Street,  will  have  connection 
of  ample  size  by  which  to  deliver  large  volumes  of  water  to  the 
Croton  system  at  Jerome  Park  Reservoir  and  the  135th  Street  gate- 
house respectively.  The  other  waterway  -hafts  will  have  connections 
not  exceeding  30-in.  in  diameter  with  the  nearby  distribution  mains 
for  the  supply  of  the  districts  in  which  they  are  situated. 

The  finished  interior  diameter  of  the  tunnel  will  be  15  ft.  from 
Hillview  Reservoir  to  Shaft  10  at  135th  Street,  a  distance  of  7.7 
miles;  14  ft.  in  diameter  from  this  point  to  Shaft  17  at  Sixth 
Avenue  and  41st  Street,  a  further  distance  of  5.0  miles;  at  Shaft 
17  the  diameter  will  be  further  decreased  to  13  ft.  and  at  Shaft  18 
at  Broadway  and  24th  Street,  0.9  mile  beyond  Shaft  17,  to  12  ft. 
This  size  will  be  carried  to  a  point  1  500  ft.  south  of  Shaft  20,  or 
about  Orchard  and  Hester  Streets,  a  distance  of  2.0  miles.  The 
remainder  of  the  tunnel  to  Brooklyn,  aggregating  2.5  miles,  will  be 
11.0  ft.  in  diameter. 

The  general  design  of  the  tunnel  differs  but  little  except  in  size 
from  the  pressure  tunnel  constructed  on  other  portions  of  the 
Catskill  Aqueduct,  one  of  which,  the  Rondout  Siphon,  was  described 
to  you  in  May,  1911,  by  Mr.  Lazarus  White,  who  now  has  charge 
of  the  southerly  division  of  the  City  Tunnel.  Typical  sections  of  the 
15-ft.  diameter  tunnel,  showing  the  lines  to  which  the  rock  is  to 
be  excavated  and  the  thickness  of  the  concrete  lining,  are  shown 
on  Plate  30,  Fig.  1.  Generally  the  type  "A"  section  is  being  adopted 
for  all  sizes  of  tunnel  and  the  thickness  of  the  lining  in  shallower 
portions  of  the  tunnel  will  not  probably  be  less  than  10  in.  to  the  "A" 
line,  and  in  the  deeper  sections  perhaps  12  to  14.  One  of  the  features 
of  the  City  Tunnel  is  the  Venturi  meter  which  is  to  be  placed  in 


70 


PROGRESS  OF  CITY  Tl'N'NKL  OF  CATSKILL  AQL'EDl  CT. 


the  tunnel  just  above  Shaft  2,  the  first  waterway  shaft,  to  measure 
the  entire  delivery  to  the  City.  The  general  design  of  the  meter  is 
shown,  Plate  30,  Fig.  2. 

The  City  Tunnel  differs  from  ether  pressure  tunnels  of  the  Cats- 
kill  Aqueduct  in  the  waterway  shafts  by  whieh  connections  are 
provided  with  the  distribution  mains.  Furthermore,  with  the  ex- 
ception of  two  section  valve  Bhafts,  L3  and  18,  to  be  hereinafter  de- 
described,  all  shafts  of  the  City  Tunnel  are  circular  instead  of 
rectangular  as  are  most  of  the  shafts  in  other  tunnels  of  the  Cats- 
kill  system  where  the  general  American  practice  was  followed.  A 
circular  waterway  shaft,  typical  of  Shafts  2,  4,  5,  G,  7,  9,  12,  14, 
15,  16,  19  and  22,  is  shown  in  Plate  31.  The  lower  portion  of 
the  shaft  is  designed  to  be  lined  with  concrete,  with  a  finished 
diameter  of  14  ft.  from  the  tunnel  to  an  elevation  roughly  100  ft. 
below  the  top  of  sound  rock.  From  this  point  to  the  surface  or 
more  properly  to  the  bottom  of  the  valve  chamber  just  below  the 
surface  at  the  top  of  the  shaft,  a  48-in.  concrete-lined  steel  riser 
pipe  is  to  be  concreted  into  the  shaft.  This  riser  pipe  will  bo 
capped  by  a  bronze  tee,  from  which  will  be  taken  each  way  a 
30-in.  connection,  to  which  will  be  attached  two  30-in.  valves  in 
tandem,  one  a  service  valve,  the  other  a  bronze  valve  attached  to 
the  bronze  tee  which  is  to  be  used  when  the  first  is  being  replaced 
or  repaired.  At  the  bottom  of  this  riser  pipe  there  will  also  be  a 
special  valve  controlled  from  the  valve  chamber  or  from  the  surface 
above  the  chamber,  which  is  designed  to  be  used  only  in  emergencies 
to  cut  off  the  flow  through  the  riser  when  the  other  valves  above  are 
out  of  order. 

The  other  waterway  shafts  have  two  risers,  Shafts  3,  8,  10,  13, 
17,  18  and  20,  of  the  same  size  as  that  described,  48  in.  in  diameter, 
and  the  terminal  shafts,  23  and  24,  2  risers  72  in.  inside  diameter. 
The  size  of  Shafts  23  and  24  are  proportionally  larger  below  the 
risers,  being  16  ft.  in  diameter.  The  design  of  one  of  the  terminal 
shafts,  24,  is  shown  in  Plate  32.  Each  of  these  terminal  shafts  has 
sufficient  capacity  to  deliver  the  full  flow  in  the  11-ft.  tunnel  should, 
by  any  chance,  any  accident  occur  to  the  other. 

At  the  so-called  section  valve  shafts,  13  and  18,  valves  or  gates 
are  to  be  built  in  the  tunnel  to  permit  of  cutting  off  the  sections 
of  the  tunnel  north  or  south  of  these  shafts.    These  shafts  are 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  71 


Plate  32. 


72       I'lax ;i;i;ss  of  city  tunnel  of  catskill  aqueduct. 


roughly  rectangular  in  shape  and  in  addition  to  a  central  well 
giving  access  to  the  section  valve  at  tunnel  grade,  there  are  to  be 
two  risers  48  in.  in  diameter  which  are  connected  to  the  tunnel  either 
side  of  the  section  valve,  as  shown  on  Plate  33. 

One  of  the  drainage  shafts.  Shaft  11,  has  no  riser,  as  already 
noted,  and  i-  almosl  identical  with  simijar  shafts  of  the  other  pres- 
sure tunnels  of  the  Catskill  Aqueduct.  This  shaft  is  l<»c;iic<l  mi 
a  lateral  drift  from  the  main  tunnel,  about  75  ft.  in  length,  and 
will  be  equipped  to  drain  the  northerly  portion  of  the  tunnel 
from  T Till  View  Reservoir  to  Central  Park.  The  other  drainage 
shaft,  21,  will  he  likewise  constructed  to  drain  the  southerly  por- 
tion of  the  tunnel,  but  this  shaft  has,  in  addition  to  the  drainage 
feature,  a  48-in.  riser  through  which  water  may  be  delivered  to  the 
distribution  system  as  at  other  waterway  shafts. 

Capacity  of  City  Tunnel. 

The  City  Tunnel  is  designed  to  carry  with  a  reasonable  loss 
of  head  the  full  capacity  of  the  Catskill  Aqueduct,  500  mil. 
gal.  per  day  from  Hill  View  Reservoir,  and  to  distribute  this 
amount  as  required  to  the  various  shafts  along  the  line.  With  a 
pressure  gradient  295  ft.  above  sea  level  at  Hill  View  Reservoir,  the 
tunnel  will  deliver  this  amount  of  water  plus  an  allowance  of 
15%  for  the  period  of  maximum  demand  at  a  pressure  in  Man- 
hattan which  will  never  be  less  than  that  corresponding  to  an  ele- 
vation of  260  ft.  above  sea  level  and  will  deliver  a  supply  of 
250  mil.  gal.  per  day  to  Brooklyn,  at  a  pressure  equivalent  to  a 
head  of  250  ft.  above  sea  level. 

Contracts  for  Tunnel. 

The  City  Tunnel  was  divided  into  4  contracts,  as  indicated  on 
Plate  29. 

Contract  63 :  City  line  to  Burnside  and  Aqueduct  Avenues, 
University  Heights  in  the  Borough  of  the  Bronx,  com- 
prising 21  270  ft.  of  15-ft.  diameter  tunnel  and  5  shallow 
shafts  (218  to  246  ft.). 

Contract  65 :  University  Heights  in  the  Bronx  to  Central  Park 
at  100th  Street,  Manhattan  Borough,  comprising  28  300 
ft.  of  tunnel  15  and  14  ft.  in  diameter  and  7  shafts,  of 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  73 


 Movable  roof  dads 


Plate  33. 


74         PROGRESS  OF  CITY  TUNNEL  01    CATSKILL  AQl'KDLXT. 


which  2  are  shallow  (262  and  278  ft.)  and  5  are  moderately 
deep  (352  to  478  ft.). 

Contract  66 :  Central  Park  at  West  100th  Street  to  Union  Square, 
Broadway  and  14th  Street,  Manhattan  Borough,  com- 
prising 23  140  ft.  of  tunnel,  14,  13  and  12  ft.  in  diameter 
and  6  shallow  shafts  (205  to  253  ft.). 

Contract  67:  Union  Square,  Manhattan  Borough,  to  the  terminal 
shafts  in  Brooklyn  Borough,  at  Flathush  and  Third  Ave- 
nues, and  at  Ft.  Greene  Park,  comprising  21  160  ft.  of 
tunnel  12  and  11  ft.  in  diameter  and  6  shafts  of  which  2 
are  shallow  (318  and  320  ft.)  and  4  arc  deep  (710  to  752 
ft.). 


Bids  were  opened  on  these  contracts  on  May  16,  1911,  and  awards 
made  to  the  lowest  bidders,  as  follows: 


Contract. 

Contractor  to  whom 
awarded. 

Amount  of  bid 
based  on  engi- 
neers" estimate  <  >f 
quantities. 

Date  Of 
award. 

Date  of  notice 
to  begin  work. 

63 

66.... 

66 

67 

Mason  &  Hanger  Co  

Pittsburg  Contracting 

Company  

Grant.  Smith  &  Co..  and 

Locher  

Holbrook.  Cabot  &  Rollins 

Corp..  T.  B.  Bryson  and 

$3  709  372 
5  590  225 

4  512  605 

5  272  435 

June  1.  1911. 
June  7,  1911. 
June  7,  1911. 

June  1.  1911. 

June  9,  1911. 
June  15,  1911. 
June  15,  1911 

June  8.  1911. 

You  will  note  that  the  cost  of  the  tunnel,  including  the  shafts 
based  on  the  amount  of  these  contracts,  gives  the  following  unit  cost 
per  linear  foot  of  tunnel : 

Contract  63. .$174. 

65.  .  197. 

66.  .  195. 

67.  .  249. 

These  prices  are  generally  higher  than  those  on  similar  pressure 
tunnels  on  the  Catskill  Aqueduct,  which  run  from  $105  to  $180 
per  foot  and  represent  not  only  the  additional  cost  of  the  compli- 
cated waterways,  the  smaller  tunnels  in  the  southerly  sections,  and 
in  the  case  of  Contract  67,  the  expensive  pneumatic  caisson  work, 
but  also  the  increased  cost  and  delay  in  doing  work  in  the  City, 
which  will  be  pointed  out  later. 


PLATE  34. 
THE    MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK. 
SPEAR  ON  PROGRESS  OF  CITY 
TUNNEL  OF  CATSKILL  AQUEDUCT. 


Fig.  2. 


FROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  75 

The  contractors  began  to  assemble  plant  early  in  June,  as  soon 
as  they  received  notice  to  begin  work,  and  with  the  exception  of 
Shaft  16  on  Contract  66  and  Shafts  21  and  23  on  Contract  67,  where 
possession  of  the  necessary  land  was  delayed  by  condemnation  pro- 
ceedings, work  at  all  shafts  was  well  under  way  by  the  last  of  July. 
The  site  of  Shaft  20  at  Delancey  and  Eldridge  Streets  was  pur- 
chased at  private  sale  and  but  little  delay  occurred.  The  com- 
missioners of  condemnation  who  were  appointed  to  appraise  the  City 
Aqueduct  real  estate  filed  their  oaths  of  office  on  August  7,  1911, 
and  after  a  necessary  interval  for  surveys  and  inspection,  the  con- 
tractors had  possession  of  all  shaft  sites  early  in  September. 

Sinking  Shafts  ix  Earth. 
The  sinking  of  the  shafts  in  earth  in  the  three  northerly  con- 
tracts, 63,  65  and  66,  offered  no  unusual  difficulties,  since  the  rock 
was  generally  found  at  or  near  the  surface  or  could  be  reached  by 
ordinary  open  cut  methods.  Before  beginning  shaft-sinking,  the 
contractors  in  most  instances  excavated  and  sheeted  the  large  cham- 
bers at  the  top  of  the  shafts  which  are  from  20  to  30  ft.  wide,  30 
to  50  ft.  long,  and  have  a  depth  of  15  to  40  ft.  below  the  surface. 
Stiff-legged  derricks  were  set  up  for  the  excavation  of  these  cham- 
bers, and  were  also  used  in  sinking  of  the  upper  portion  of  the 
shafts.  Plate  34,  Fig.  1,  shows  the  sheeting  and  timber  in  the  cham- 
ber at  Shaft  17  which  is  typical  of  most  of  the  chamber  excavations. 
The  steel  sheeting  and  timber  bents  which  were  put  in  at  Shaft  5 
below  the  chamber  excavation  to  reach  the  rock  is  seen  in  Plate 
34,  Fig.  2.  Special  care  was  exercised  at  this  shaft  to  prevent  any 
loss  of  ground,  because  the  old  Croton  Aqueduct  is  on  an  earth  em- 
bankment only  20  ft.  away.  No  settlement  occurred  about  the  ex- 
cavation and  after  the  concrete  lining  was  placed  the  steel  sheeting 
was  removed  and  grout  forced  into  the  ground  outside  of  the  con- 
crete walls.  Steel  sheeting  was  also  employed  in  the  earth  portion 
of  Shaft  18,  where  the  rock  was  30  to  40  ft.  below  the  surface. 

Pneumatic  Caissons. 

At  the  shafts  of  Contract  67  the  rock  floor  is  covered  by  some 
depths  of  generally  pervious  earth,  of  which  30  to  100  ft.  are  below 
the  water  table,  and  the  shafts  are  situated  in  localities  where  seri- 
ous damage  might  have  resulted  from  attempting  to  reach  the  rock 


7G        PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT. 

by  means  of  sheeted  excavation  or  open  caissons.  Pneumatic  caissons 
were  accordingly  sunk  to  rock  and  sealed  in  before  the  rock  shafts 
were  started.  Five  of  these  caissons  were  constructed  entirely  of 
reinforced  concrete  with  V-shaped  cutting  edges  made  up  of  plates 
and  structural  steel;  three  of  these  caissons,  those  at  Shafts  19, 
20  and  22,  had  an  outside  diameter  of  19  ft.  4  in.,  and  walls  2  ft.  in 
thickness;  and  two  of  them,  those  at  Shafts  23  and  24,  had  outside 
diameters  of  24  ft.  and  walls  3  ft.  in  thickness.  Plate  35,  Fig.  1, 
shows  the  top  of  one  of  these  larger  caissons  at  Shaft  24  with  hori- 
zontal and  vertical  reinforcements  in  place  ready  for  concreting. 
These  vertical  reinforcing  rods  have  sleeve  nuts  projecting  through 
slots  in  the  inner  sloping  face  of  the  cutting  edge,  to  which  other 
rods  of  the  same  diameter  will  subsequently  be  connected  and  con- 
creted into  the  rock  shaft  below7  to  prevent  the  overturning  of  the 
caisson  and  the  rupture  of  the  lining.  Plate  35,  Fig.  2,  presents  a 
view  at  the  bottom  of  the  same  caisson  where  rods  to  be  bent  out 
to  hold  the  deck  have  been  exposed. 

The  steel  cutting  edges  of  these  caissons  were  first  erected  upon 
the  bottom  of  the  chamber  excavation  and  the  caissons  were  alter- 
nately concreted  and  sunk  of  their  own  weight  until  the  water  table 
was  reached.  With  the  exception  of  the  caisson  at  Shaft  23  all 
of  the  concreting  of  the  wall  of  the  caissons  was  done  before  build- 
ing the  concrete  deck  and  putting  on  the  air,  for  the  reason  that 
there  would  have  been  serious  delay  and  some  danger  in  interrupt- 
ing the  sinking  to  concrete  after  having  once  started.  Plate  36, 
Fig.  1,  shows  the  caisson  at  Shaft  23  when  completed  ready  for  com- 
pressed air.  This  is  the  deepest  of  the  six  caissons,  118  ft.,  of  which 
when  this  photograph  was  taken,  40  ft.  were  in  the  ground. 

With  the  exception  of  Shaft  19,  the  shallowest  caisson,  the  con- 
tractor installed  two  shafts  in  each  caisson  with  a  Mattsen  lock  of 
50  or  110  cu.  ft.  capacity  on  each.  The  general  design  of  these 
caissons,  the  location  of  the  deck,  the  shafting  and  the  locks  are 
seen  in  Plate  37  which  shows  a  section  of  the  caisson  at  Shaft  20. 
One  of  the  two  locks  of  the  smaller  size  at  this  shaft  was  used  for 
materials  and  the  other  for  the  men.  Except  for  the  deeper  shafts 
no  bucket  was  used  in  the  man  lock,  the  men  using  the  ladderway 
in  passing  in  or  out.  In  the  deepest,  however,  that  at  Shaft  23,  two 
locks  of  the  larger  size  were  used  at  the  beginning  for  the  removal 


PLATE  35. 
THE    MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK. 
SPEAR  ON  PROGRESS  OF  CITY 
TUNNEL  OF  CATSKILL  AQUEDUCT. 


Fig  2. 


PLATE  36. 
THE    MUNICIPAL  ENGINEERS 
OF  THE  CITY  OF  NEW  YORK. 
SPEAR  ON  PROGRESS  OF  CITY 
TUNNEL  OF  CATSKILL  AQUEDUCT. 


Fig.  2. 


fkookfs.s  of  i  itv  ti  nnkl  of  catskill  AQUEDUCT. 


of  the  excavation,  but  as  the  pressure  increased  one  was  reserved 
entirely  for  the  men  and  they  were  taken  in  and  out  in  a  bucket. 
The  general  dimensions  ami  weights  of  each  caisson,  the  maximum 
air  pressures  used  and  the  frictional  resistances  estimated  at  the 
times  of  movement  of  the  caisson  when  bottom  free  ami  clear  are 
shown  in  the  following  table: 


Caisson  shaft. 

<  >ut<ide  diam- 
eter, tV»>t . 

»-  = 

I  1'- 

h| 

5si . 

m 

z  ~  ~  -~ 

g  S  S  J 

-~  ci 

u-i  . 
:  •-  / 

~~  ~ 
§  =  ~ 

'I  -7.  -' 
>  /  ^ 

"  a  ■ 
B 

ti 

a-  — 

)s  - 
~  = 

l>  - 

Hi . 

E  -  ' 
-  .-  "r  | 

*  * 

Estimated  fric- 
tion and  penetra- 
tion resistance. 
Lbs.  per  sq.  ft., 
making  allow- 
ance for  air 
pressure. 

19 

19.8 

2.0 

46.1 

466 

700 

R 

300  to  400 

80 

19.8 

2.0 

1C2.0 

1  <  >.-,« » 

2  luO 

39 

630 

22 

19.3 

2.0 

96.0 

978 

2  470 

28 

630  to  736 

23  .... 

24.0 

3.0 

117.6 

2  323 

4  612 

45 

sTn  tO  1  450 

24 

24.0 

3.0 

95.4 

1  780 

4  046 

29.5 

945  to  1  685 

You  will  note  that  the  frictional  resistance  on  these  circular  caissons  rauged  from 
300  lb.  to  1  6K5  lb.  per  sq.  ft.  Tnis  wide  range  is  probably  to  be  explained  by  tne  differ- 
ence in  the  sizes  of  caissons  and  in  the  material  encountered,  by  slight  irregularit  m 
some  of  the  casings,  the  depth  of  penetration  of  the  cutting  edge  below  the  excavation 
in  the  working  chamber  and  the  straightness  with  which  the  caisson  was  sunk. 

Good  progress  was  made  in  sinking  the  caissons  in  earth.  The 
average  advance  of  the  5  circular  caissons  was  8|  ft.  per  24  hours; 
the  record  progress  was  made  at  Shaft  20,  where  the  caisson  was 
dropped  10.9  ft.  in  24  hours. 

The  method  of  sealing  these  concrete  caissons  into  the  rock  is 
by  far  the  most  interesting  feature  of  the  work  and  the  most  difficult. 
The  work  had  to  be  done  under  the  highest  pressure  and  on  the 
average  only  8  cu.  yds.  of  rock  could  be  excavated  daily:  including 
the  time  from  the  beginning  of  the  excavation  of  the  rock  to  taking 
off  the  pressure  the  sealing  took  about  three  weeks.  The  method 
of  sealing  is  shown  in  detail  on  Plate  38.  When  the  rock  had  been 
excavated  to  the  required  depth,  which  was  fixed  at  5  ft.  below 
the  lowest  point  of  the  rock  at  the  cutting  edge,  the  bottom  was 
leveled  up,  a  bench  of  concrete  was  placed  a  foot  thick  around  the 
shaft  with  wood  blocks  set  under  the  cutting  edge  to  receive  the 
shock  of  the  dropping  caisson,  and  a  collar  of  1 :  2  mortar  carried 
up  to  3  ft.  above  this.  In  this  collar  and  passing  through  the  bench 
at  least  six  2-in.  grout  pipes  were  set  as  shown,  communicating  with 
the  three  horizontal  grooves  formed  in  the  ring  for  the  purpose 
of  insuring  a  free  circulation  of  the  grout  around  the  caisson.  The 
caisson  was  lowered  to  the  bench  after  the  cement  had  set.  a  ring 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT. 


79 


-Position  of  shoe  when  mortar  is 


^8 -2" grout  pipes  around  perimeter 
at  5  'aboue  shoe 


f  %  \      i  "clearance  . 

m 


^8-2  'grout  pipes  around  perimeter 
at  3'  above  shoe 


2' grooves  in  mortar  collar  tormed 
by  nailing  i  round  strips  fo  form. 
Vertical  grooves,  every  6  ft.  around 
perimeter,  connect  the  horizontal  groooes 
the  whole  forming  a  q routing  drainage 
system.  Just  prior  to  grouting,  air  is  blow 
in  to  clean  surfaces. 


-Oakum 

Steel  plate z  'thick 

total  of  6-2' pipes  around  perimeter, 
two  at  each  groove. 

'6  x  6  wooden  blocks  capped  with  3  "steel     K  kVV  ' 
plate,  placed  at  4'  intervals  to  receive  shock  of  dropping 
caisson.  Five  inches  of  oakum  placed  under  the  entire 
perimeter  prior  to  dropping,  to  insure  water  tightness.  After 
caisson  is  dropped,  grouting  is  immediately  started. 

d'-O" collar  may  be  reduced  to  ZH) "collar 
depending  on  rock  conditions  and  ground 
Drowned  water  level 


Traced  cJ.&d. 
Cached 


C.ty  of  New  York 
BOARD  OF  WATER  SUPPLY 

CATSKILL  AQUEDUCT 

CITY  TUNNEL 
CONTRACT  67   SECTION  S 
COMPRESSED  AIR  WORK 
SEALING  CAISSON  IN 
EARTH  TO  ROCK 
SCALE  r=r 

NOVEMBER  3,  I9U 

File  c-~'  fcT  s.4rMC'°>  acccmtso. 


Plate  38. 


(SO       i'i:o<;Ki;ss  of  city  ji  nm  i.  of  catskiu.  aqi  fdlct. 


of  oakum  being  placed  to  make  a  temporary  seal  and  the  space 
between  the  outer  wall  of  the  cutting  edge  and  the  ring  was  grouted 
with  neat  cement.  Other  grout  pipes  through  the  walls  of  the 
caisson  wore  thou  filled  and  after  the  expiration  of  something  like 
12  hours  the  pressure  was  taken  oft'.  On  the  average  3  days  were 
required  to  place  the  concrete  bench  and  collar,  and  to  lower  and 
grout  the  caisson.  In  the  case  of  one  caisson,  that  at  Shaft  20,  the 
leakage  through  the  seal  when  the  pressure  was  removed  was  only  10 
gallons  per  24  hours,  and  the  maximum  leakage  at  Shaft  213,  the 
deepest  earth  shaft,  was  only  7  gallons  per  minute,  which  was  sub- 
sequently grouted  off.  The  mass  of  those  loaded  caissons  was  such 
that  it  was  exceedingly  difficult  to  keep  them  plumb,  and  more  diffi- 
cult to  right  them  when  once  out  of  perpendicular.  The  maximum 
deviation  from  the  perpendicular  on  the  length  of  the  caissons  was 
about  8  in.  in  case  of  caisson  at  Shaft  24,  which  was  !).*)  ft.  deep, 
while  the  caisson  at  Shaft  20,  102  ft.  long,  went  down  practically 
plumb,  as  shown  below: 


Shaft. 

Outside  Diameter 
of  caisson, 
feet. 

Total  depth 
of  caisson, 
feet. 

Amount,  in  Inches,  by  which  Caisson 
was  out  of  Plumb  when  Sealed. 

In  total  length. 

Per  foot  of 
length. 

19.... 
20. . . . 
22. . . . 

24.... 

19.3 
19  3 
19.3 
24.0 
24.0 

46.1 
102.0 

96.0 
117.6 

95.4 

1.00 
1 .00 
7.37 
6.72 
7.90 

0.022 
0.010 
0.074 
0.055 
0.075 

Shaft  21  differs  materially  from  the  other  five  shafts  of  Contract 
07,  because  of  the  support  which  it  was  necessary  to  provide  for 
the  superstructure  over  the  drainage  chamber  at  the  top  of  the  shaft; 
instead  of  a  single  caisson  to  rock  for  the  shaft  and  a  number  of 
smaller  caissons  to  carry  the  superstructure  the  contractor  chose 
the  alternative  permitted  under  the  contract  of  sinking  and  excavat- 
ing to  rock  four  rectangular  concrete  filled  wooden  caissons  37  ft. 
to  43  ft.  in  length,  and  5  ft.  thick,  on  which  the  superstructure  will 
be  built. 

These  caissons,  with  half -moon  closures,  are  shown  in  plan  on 
Plate  39.  The  rock  here  was  only  30  to  40  ft.  below  the  surface 
and  these  caissons,  which  were  made  37  ft.  high,  were  sunk  without 
incident.    The  frictional  resistance  was  about  1  200  lb.  per  sq.  ft. 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  81 


82 


PROGRESS  OF  CITY  TUNNEL  OF  CAT8KILL  AQUEDUCT. 


The  grano-diorite,  when  uncover* d,  was  found  to  he  hard  hut  seamy  ; 
eonsiderahle  water  entered  through  the  bottom  of  the  excavation 
and  came  in  at  the  corners  of  the  caissons  where  not  tightly  sealed 
on  the  rock.  Some  leakage  also  entered  the  upper  portion  of  the 
shaft,  as  it  was  excavated,  and  it  was  necessary  to  put  in  a  tem- 
porary lining  in  the  shaft,  place  a  blanket  of  concrete  over  the 
entire  bottom  of  the  excavation  within  the  wall  caissons,  and  grout 
off  the  leakage. 
Shafts  in  Rock. 

The  sinking  of  the  shafts  in  rock  has  been  carried  on  during 
the  entire  24  hours  of  each  working  day,  with  3  shifts  of  men.  The 
force  employed  at  a  well-organized  shaft  is  shown  below.  This  is 
a  circular  shaft,  in  Manhattan  schist,  18  ft.  in  diameter. 


General: 

Superintendent   2 

Timekeeper    1 

Storekeeper    2 

Watchman    2 

Magazine  tender    2 

Foreman   1 

Rigger    4 

Carpenter    4 

Laborer    4 

Bottom  of  Shaft: 

Shift  boss    3 

Drill  runners    9 

Muckers     19 

Top  of  Shaft: 

Foreman   2 


Compressor  engineer   3 

Blacksmith    3 

Blacksmith's  helper    3 

Electrician   3 

Top  man    4 

Signalman    3 

Hoist  runner   3 

Pipeman    6 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  83 


Much  Bins : 

Team  and  driver 
Laborer  


4 


1 


Total 


Practically  all  of  the  drilling  was  done  by  this  organization 
during  the  12  midnight  to  8  a.  M.  shift;  8  cut  holes  and  one  center 
hole  were  shot  about  7:30  a.  m.;  after  mucking  out,  14  relief  holes 
were  fired,  about  noon,  and,  after  mucking,  the  20  rim  holes  were 
fired,  about  4:30  p.  M.  Six  Ingersoll  Eotating  Hammer  drills  were 
used;  the  cut  holes  were  drilled  8  ft.  in  depth,  the  relief  holes  7.5, 
and  the  rim  holes  7.0  ft.  310  ft.  of  holes  were  drilled  per  round. 
An  average  advance  of  6.0  ft.  was  made  each  round,  and  1.9  lb.  of 
60%  dynamite  per  cu.  yd.  were  used. 

On  Plate  40  is  shown  the  arrangement  of  drill  holes  in  the  shafts 
of  Contract  66.  This  arrangement  is  practically  the  same  as  that 
followed  in  the  shafts  of  the  other  contracts.  You  will  note  that 
30  to  40  holes  were  drilled  in  one  round  in  the  circular  shafts  and 
43  to  46  in  rectangular  shafts;  4  to  6  ft.  were  pulled  at  each 
advance.  The  amount  of  dynamite  used  at  the  shafts  in  the  built-up 
portions  of  the  city  averaged  from  1.5  to  2  lb.  per  cu.  yd.  excavated. 
At  some  shafts,  located  at  a  safe  distance  from  buildings,  where  the 
rock  was  harder,  3  to  3£  lb.  of  dynamite  were  used.  Both  40%"  and 
60%  dynamite  were  used. 

Records  of  25  to  30  ft.  per  week  have  been  frequently  made  in 
the  shafts  of  the  City  Tunnel,  but  the  best  record  thus  far  made 
was  at  Shaft  10,  where  an  advance  of  37  ft.  per  week  was  made. 
The  progress  per  month  has  not  approached  the  record  made  at  the 
other  tunnels  of  the  Catskill  Aqueduct,  principally  because  of  the 
short  depths  of  the  shafts  thus  far  completed,  which  did  not  permit 
of  effecting  the  necessary  organization,  and  because  of  the  frequent 
interruptions  and  the  consequent  disorganization  of  the  drilling 
and  mucking  force  resulting  from  the  interruptions  necessary  to 
concrete  the  shaft  at  intervals  of  100  ft.  The  best  month's  work 
thus  far  recorded  was  108  ft.,  which  was  done  at  Shafts  8  and  10 
of  the  Pittsburg  Contracting  Company's  contract,  though  a  some- 
what better  performance  was  made  at  Shaft  20,  one  of  the  shafts 


84        PROGRESS  OF  CITY  TUNNEL  OF  CAT8KILI  AQUEDUCT. 

<it  Holbrook,  Caboi  &  Rollins  Corp  oration  contract,  where,  in  addi- 
tion to  LOO  ft  of  shaft  sinking,  <;;,  ft  of  the  shaft  was  concreted 
in  a  month.  A  record  of  96  ft.  in  three  weeks  was  made  at  Shaft 
14  by  the  Dravo  Contracting  Company,  who  were  sinking  this  shaft 
for  Grant,  Smith  &  Company  and  Locher. 

The  progress  that  has  been  made  in  shaft  sinking  to  date  is 
summarized  in  the  following  table: 


Progress  in  Excavating  Rock  Shafts. 


Contract  No. 

Shaft  No. 

Average  speed, 
in  feet  per 

month,  includ- 
ing time  of 
concreting. 

Maximum 
weekly  progress, 
in  feet. 

Maximum 
monthly  pro- 
gress, la  feet. 

03  

1 

87.8 

M 

59 

2 

22 

62 

8 

52.0 

33 

75 

4 

47.0 

32 

80 

5 

51.3 

■  9 

62 

65  

6 

40.8 

2» 

70 

7 

47.0 

25 

?5 

8 

97.8 

32 

108 

9 

45.0 

22 

73 

10 

70.8 

37 

108 

11 

57.2 

26 

80 

IS 

48.0 

21 

52 

66  

18 

40.0 

26 

55 

14 

86.0 

33 

100 

15 

68.0 

32 

95 

16 

76.0 

28 

87 

17 

57.8 

24 

65 

18 

51.0 

15 

53 

67  

19 

78.0 

30 

75  • 

30 

100.0 

35 

100 

21 

58.8 

25 

78 

22 

73.0 

27 

78 

28 

82.0* 

21 

24 

56.9 

24 

ei 

*  Two  weeks  only. 


The  rock  shafts  have  been,  on  the  whole,  dry,  and  the  rock,  gen- 
erally, sound.  The  rock,  however,  has  ordinarily  a  dip  in  excess  of 
45°,  and  shows  evidence  in  places  of  much  folding  and  slipping. 
At  Shaft  4,  at  the  lower  end  of  Jerome  Park  Reservoir,  bad  ground 
was  encountered  not  far  above  the  tunnel  grade.  Fifty  holes  were 
drilled  at  the  bottom  of  the  excavation,  and  over  900  bags  of  neat 
cement  were  used  in  grouting,  before  the  water  was  cut  off.  When 
the  shaft  was  finally  sunk  through  the  wet  ground  it  was  found  that 
the  rock  was  badly  broken,  and  there  was  one  seam  in  which  the 
rock  had  so  much  disintegrated  that  there  was  little  left  but  sand. 


SG 


PROGRESS  OF  CITY  TUNNEL  01  CAT8KILL  LQUEDUOT. 


This,  and  the  other  thin  seams  which  were  filled  with  the  same  ma- 
terial, did  not  take  the  grout  readily,  and  this  fact  accounts  for  the 
largo  number  of  boles  that  were  necessary.  Alter  the  slaii't  was 
excavated  some  10  ft.  below  the  bad  ground,  a  thick  reinforced  con- 
crete lining  was  placed  and  the  ground  behind  filled  with  grout. 
Somewhat  similar  ground  was  found  nt  Shaft  24,  in  Fort  (Jreene 
Park,  Brooklyn,  and  the  grouting  appears  to  have  been  equally 
successful. 

As  stated  above,  the  placing  of  the  concrete  lining  has  interfered 
somewhat  with  rapid  progress  on  the  City  Tunnel  shafts;  in  most 
shafts,  however,  the  rock  was  Buch  that  some  support  would  have 
been  necessary  at  frequent  intervals,  so  that  time  lost  in  concreting 
was  more  apparent  than  real. 

The  concrete  lining  of  the  lower  portions  of  the  shafts  below 
the  river  valves  represented  the  finished  lining  of  the  final  water- 
way. Only  the  irregular  section  valve  shafts,  13  and  18,  were  tim- 
bered. The  experience  on  this  work  has  demonstrated  the  ad- 
vantages of  the  concrete  lining;  it  gives  no  trouble  after  once  in 
place,  and  effectually  cuts  off  the  inflow  of  water  to  the  shaft.  The 
method  of  making  a  closure  in  the  concrete  lining  is  shown  in 
Plato  41. 

Progress  on  Tunnel. 

The  first  shot  was  taken  from  the  tunnel  heading  at  Shaft  14 
on  December  6,  1911,  and  the  tunnels  were  started  at  other  shafts 
shortly  after  that  date.  At  present,  16  of  the  24  shafts  have  been 
completed  to  tunnel  grade,  and  at  some  of  the  shafts  the  tunnels 
are  well  under  way.  Ordinarily,  from  two  to  six  weeks  has  been 
required  after  the  completion  of  the  shaft  to  change  over  equipment 
and  install  cages  in  readiness  for  tunnel  driving.  The  progress 
on  the  tunnels,  even  where  the  headings  are  at  some  distance  from 
the  shaft,  has  not  yet  equalled  the  record  made  on  other  parts  of 
the  Catskill  work.  A  number  of  circumstances  have  contributed 
to  this  comparatively  small  progress,  such  as  are  necessarily  inci- 
dent to  the  execution  of  shaft  and  tunnel  excavation  through  the 
heart  of  our  great  city. 

The  storage  of  the  amount  of  dynamite  required  for  a  tunnel 
of  the  size  of  the  City  Tunnel,  constructed  in  the  midst  of  con- 
gested business  and  residential  districts,  has  presented  a  serious 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  87 


S8 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT. 


problem  for  those  having  the  responsibility  in  such  matters.  Only 
150  to  200  pounds  of  powder  were  allowed  to  be  stored  during  the 
shaft-sinking  period,  and  only  400  pounds  are  now  permitted  tem- 
porarily in  the  surface  magazines.  The  Municipal  Explosives  Com- 
mission has  approved  underground  magazines  excavated  in  the  rock 
at  the  end  of  a  drift  75  ft.  in  length,  the  entrance  to  which  from  the 
tunnel  will  not  be  less  than  100  ft.  from  the  foot  of  the  shaft.  This 
magazine  is  to  have  a  heavy  door,  hung  in  a  concrete  bulkhead,  at 
the  entrance  to  the  magazine  drift,  which  is  designed  to  close  when 
an  explosion  occurs  in  the  magazine  and  prevent  the  escape  of  the 
gases  of  combustion  in  the  magazine  and  minimize  the  rush  of  air 
up  the  shaft.  The  design  of  this  magazine  has  been  worked  out  by 
the  engineers  of  the  City  Aqueduct  Department  and  is  based  on 
French  and  German  practice.  A  number  of  these  magazines  are 
under  construction,  and  one  of  them,  that  at  Shaft  18,  is  practically 
finished. 

Disposal  of  Excavation. 

The  contractors  on  the  lower  sections  of  the  City  'runnel  have 
encountered  no  more  serious  problem  than  that  of  disposing  of  the 
materials  excavated  from  the  shafts  and  tunnels.  At  the  first  four 
shafts,  1  to  4,  inclusive,  it  was  possible  to  find  areas  adjacent  to  or 
near  the  shaft  sites  on  which  the  earth  and  rock  could  be  spoiled 
at  comparatively  little  expense;  but  at  the  other  shafts  it  has  been 
necessary  to  haul  everything  to  the  waterfront,  or  other  points  of 
disposal  at  some  distance  from  the  shaft.  On  Contract  65,  through 
an  arrangement  with  the  Park  Department,  a  large  amount  of  the 
excavation  is  being  dumped  along  the  Xorth  River  near  129th 
Street,  to  fill  an  area  on  the  river  front  that  is  being  reclaimed  for 
a  park.  A  portion  of  the  excavation  on  Contract  66  has  gone  to 
make  a  fill  at  the  foot  of  West  79th  Street,  but  more  of  it  is  going 
to  the  docks,  to  be  carried  to  sea,  and  much  of  that  on  Contract  67 
is  being  similarly  disposed  of. 

Plant  Layouts. 

The  amount  of  land  available  to  the  contractors  about  the  shafts 
of  the  City  Tunnel  was  necessarily  limited  in  some  localities  to 
hardly  5  000  sq.  ft.,  and  it  is  interesting  to  see  how  the  contractors 
have  arranged  their  plants  on  such  small  spaces.    Plate  42  shows 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT. 


S9 


'JO        PEOGBB8S  OB  CITY  TUNNEL  OP  OATSKILC  AQUEDUCT. 


the  arrangement  of  the  contractor's  plant  at  Shalt  19  and  the 
Bowery,  during  the  period  of  sinking  this  shaft  in  rock.  This  is  a 
good  example  of  a  small  space  well  utilized.  Referring  to  this  plant, 
you  will  see  that  the  compressors,  blacksmith  shop,  cement  shed, 
store  house,  contractor's  office,  and  drives  occupy  the  ground  level, 
while  on  the  deck  above  are  the  hoists,  repair  shops,  shelter  for 
men,  dynamite  magazine,  and  engineer's  and  doctor's  office,  and  open 
storage  room  for  forms  and  other  equipment.  The  equipment  for 
sinking  this  shaft  and  placing  the  concrete  lining  is  tabulated 
below : 


Siiait-Sixkinc  Plant. 


Manufacturer. 

Size. 

Operating  mechanism. 

Head  frame. . 

Compound 
compressor 

Compound 
compressor 

Exeter  Machine  Works.. - 

\  Lackawanna   Bridge  ) 

1    Co  I 

, 

Ingersoll-Rand  Co  

1 
1 

1 

Single.  5  ft.  diam. 
by  4    ft.  6  in. 
geared  drum  

76  ft.  high  15*  tons-| 

181  in.  and  111  in.  | 
cylinders.  16  in. 
stroke.  900 cu.  ft.  \ 
free  air  per  min-  I 

1    ute  J 

21  i  in.  and  12}  in. } 
cylinders,  18  in.  | 
stroke.  1  30(j  cu.  f 
ft.  free  air  per  j 

Direct  connected  Q  E  in- 
duction motor;  112  h.p.; 
440  volts. 

Constructed  for  double 
balanced  cages  when 
tunneling. 

Direct  connected   G.  E. 
synchronous  motor:  164 
h.  p  ;  6  600  volts:  with 
6g  kw.— 125-volt  exciter. 

Direct   eonnecte  1  G.  K. 
synchronous  motor:  215 
b.  p.;  6  600  volts,  with 
9i  kw.-  125-volt  exciter. 

Manufacturer. 

Number  aDd 

size. 

Operating  mechanism. 

Hard  ham- 
mer drills.. 

Sinking 

f  Ingersoll-Rand  Co  I 

IMcKiernan  Terry  <  n 

\     Drill  Co  j  J 

1  Sullivan   Machinery  /  n 

[    Company  \ 

*  Cameron  Steami  1 
/     Pump  Works  f 

^our  96  lb  

rwo521b  

rhree  41  lb  

2  x  5  x  13  in.  stroke, 
100  gallons. 

Machine  rotating  bit. 
Hand  rotating  bit. 

Hand  rotating  bit. 

Shaft  Concreting  Plant. 

Concrete 

mixer. . 

j  Ransome    Concrete  )  . 
*    Machine  Co  )' 

r  3 
i 

1  Blaw  Collapsible! 
I    Steel  Centering  Co.  j 

I 

cu.  yd.  capacity... .  -j 

5  ft.  of  forms  equals 
28  pieces.  Thickness 
of  plate  =  Ys  in.  In- 
terior bracing  of  4 
curved  6  in.  channels 
and  3  x  2  in.  angles. 

Direct  connected  G.  E.  di- 
rect   current,   25  h.p. 
motor,  240  volts. 

PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  91 


In  Plate  36,  Fig.  2,  is  seen  a  photograph  of  Shaft  19,  taken 
from  the  west,  which  shows  the  hoist,  head-frame  and  muck  bins  in 
place  for  shaft-sinking.  But  little  will  have  to  be  done  here  when 
the  shaft  is  completed  to  prepare  for  tunnel  driving,  except  to  in- 
stall the  cages  and  tipples. 

Power  Plants. 

In  drawing  up  contracts  for  the  City  Tunnel,  it  was  planned 
to  eliminate,  as  far  as  possible,  any  annoyance  to  the  public  from 
noise,  smoke  and  dust  arising  from  the  prosecution  of  the  work, 
particularly  at  the  shafts  in  the  built-up  sections  of  the  city, 
by  requiring  that,  so  far  as  practicable,  electric  power  be  used  in- 
stead of  steam.  On  Contract  63,  that  of  Mason  &  Hanger  Com- 
pany, comprising  Shafts  1  to  5,  inclusive,  which  are  located  in  the 
undeveloped  portions  of  the  city,  steam  power  has  been  largely 
used;  through  arrangements  made  between  the  contractor  and  the 
Park  Commissioner  of  the  Bronx,  the  contractor  agreed  to  fill  for 
the  city  a  large  area  of  swamp  in  Van  Cortlandt  Park,  without 
other  consideration  than  that  he  be  allowed  to  locate  there  a  cen- 
tral steam  compressor  plant  and  to  lay  pipes  through  the  park 
in  which  to  distribute  the  air  to  the  five  shafts  of  his  contract. 
This  compressor  plant,  which  has  a  capacity  of  12  500  cu.  ft.  of 
free  air  per  minute,  has  been  in  operation  for  several  months,  and 
compressed  air  is  used  at  the  shafts  of  this  contract  for  drills  and, 
to  some  extent,  for  pumping.  Steam  hoists  were  used  temporarily 
for  sinking  the  shafts,  but  the  permanent  hoists  are  operated  by 
electricity  and  some  pumping  is  being  done  by  electrically-driven 
pumps.  By  the  above  plan,  all  smoke  and  dirt  is  confined  to  the 
central  power  plant,  which  is  located  in  a  section  of  the  park  where 
no  annoyance  can  arise. 

On  the  next  contract,  65,  that  of  the  Pittsburg  Contracting 
Company,  comprising  Shafts  7  to  12,  inclusive,  no  steam  plants 
have  been  used;  even  the  temporary  hoists  were  driven  electrically. 
Ingersoll-Band  motor-driven  compressors,  having  a  capacity  of 
350  cu.  ft.  of  air  per  minute,  sufficient  for  the  hand-hammer  drills 
used  in  shaft-sinking,  have  been  placed  at  five  of  the  shafts;  but 
two  of  the  shafts,  9  and  11,  have  been  sunk  entirely  by  electric 
drills,  and  no  compressors  have  been  installed. 

On  Contract  66,  that  of  Grant,  Smith  &  Company  and  Locher, 


92 


['Ko<;j;i;ss  of  city  tiwkl  of  catskill  A.QUEDUOT, 


compressed  air  for  the  operation  of  the  drills  is  being  supplied  to 
the  first  three  shafts,  13,  14,  and  15,  from  a  central  compressor 
plant  equipped  with  three  electrically-driven  two-stage  compressors 
of  the  Sullivan  Machinery  Company,  having  a  total  capacity  of 
6  300  cu.  ft.  of  free  air  per  minute.  This  plant  is  located  in  Cen- 
tral Park,  within  the  contractor's  enclosure,  at  Shaft  14,  and  the 
air  is  piped  through  the  transverse  roads  and  along  the  sidewalk  of 
Eighth  Avenue  to  the  other  two  shafts.  At  the  three  southerly 
shafts  of  this  contract,  1G,  IT,  and  18,  and  in  all  six  shafts  of 
Contract  67,  Shafts  19  to  24,  inclusive,  which  is  being  carried  on 
by  Holbrook,  Cabot  &  Rollins  Corporation,  each  shaft  has  an  inde- 
pendent electrically-driven  compressor  plant,  comprising,  on  Con- 
tract G6,  a  single  Ingersoll-Rand  two-stage  machine  of  a  capacity 
of  2  100  cu.  ft.  of  free  air  per  minute,  and  on  Contract  67  two 
Ingersoll-Kand  two-stage  compressors,  one  of  a  capacity  of  1 200 
cu.  ft.  and  the  other  900  cu.  ft.  of  free  air  per  minute. 

Alternating  current  is  supplied  to  the  shafts  in  the  Boroughs  of 
Manhattan  and  the  Bronx  by  the  New  York  Edison  Company  and 
its  subsidiaries,  and  to  those  in  Brooklyn  by  the  Edison  Electric 
Illuminating  Company  of  Brooklyn,  at  a  voltage  of  about  6  600. 
This  current  is  stepped  down  to  2  200  for  the  hoists  and  compressors 
on  Contract  65,  and  to  220  volts  for  power,  lights  and  blasting  on 
Contracts  63  and  65.  The  alternating  current  at  6  600  volts  is 
delivered  directly  to  the  compressors  on  Contracts  66  and  67,  and 
from  this  reduced  to  a  voltage  of  440  and  220  for  power,  and  to  about 
110  for  lighting  and  blasting.  Direct  current  at  about  220  volts  is 
used  for  the  hoists,  at  110  volts  for  lights  and  small  motors  on  Con- 
tracts 66  and  67. 

Cages  and  Hoists. 

The  shafts  thus  far  completed  have  been  equipped  with  single- 
drum  Flory  and  Lidgerwood  hoists,  which  are  capable  of  operating 
at  a  speed  of  400  ft.  per  minute  two  balanced  cages,  each  with  a 
5  x  8-ft.  platform.  On  two  contracts,  65  and  67,  platform  cages, 
weighing  about  3  000  lb.,  are  to  be  installed ;  on  the  other  two,  63 
and  66,  self-dumping  cages,  weighing  about  4  500  lb.,  are  being 
put  in.  The  safety  devices  on  all  cages  are  tested  as  soon  as  in- 
stalled, and  at  frequent  intervals  thereafter,  and  the  hoists  are 
being  equipped  with  devices  to  prevent  overwinding  of  cables. 


PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  93 


Drills. 

On  Contracts  63  and  66,  and  to  a  large  extent  on  Contract  67, 
large  3:1-  and  3§-in.  piston  drills,  mounted  on  tripods,  have  been 
used  for  sinking  the  shafts.  On  Contract  65,  however,  the  Pitts- 
burg Contracting  Company  has  successfully  used,  on  5  of  their 
7  shafts,  several  kinds  of  hand-hammer  or  Jap  drills,  including 
the  Sullivan  drill,  which  weighs  about  60  lb.,  and  the  larger 
Ingersoll  Rotating  drill,  which  has  a  weight  of  about  90  lb.  The 
use  of  these  large  hand  drills  marks  a  distinct  advance  in  shaft- 
sinking  methods.  Among  their  advantages,  it  should  be  noted  that 
the  hand  drill  requires  for  its  operation  but  one  drill-runner,  with- 
out a  helper;  the  drill  is  easily  handled  in  the  shaft;  no  time  is  lost 
in  setting  it  up  or  moving  it,  and  it  may  be  operated  while  mucking 
is  going  on.  The  drill  cuts  fully  as  fast  as  the  large  tripod  drill, 
with  much  less  air,  and  little  trouble,  other  than  with  the  drill 
steel,  is  experienced  in  drilling  7-ft.  to  8-ft.  holes  in  moderately 
hard  rock.  Of  course,  the  hand  drill  makes  a  smaller  hole  than  the 
larger  piston  drill.  The  rotating  Jap  drills  are  also  being  used 
successfully  on  Contract  67,  but  in  the  hard  granitic  rock  of  the 
Brooklyn  shafts  their  use  has  been  confined  to  trimming  holes,  the 
cut  and  reliever  holes  being  drilled  with  3|-in.  piston  drills, 
mounted  on  tripods. 

Three  types  of  electric  drills  have  also  been  used  on  Contract  65, 
the  Fort  Wayne,  the  Pneumelectric,  and  the  Dulles-Baldwin.  The 
second  type  of  drill  is  used  in  sinking  Shaft  11,  and  the  last  in 
sinking  Shaft  9.  Alternating  current  at  220  volts  is  delivered  to 
these  drills  through  a  cable  and  manifold  suspended  from  the  top 
of  the  shaft.  The  electric  drills  effect  a  large  saving  in  power,  and 
no  doubt,  when  perfected,  this  type  of  drill  will  have  a  large  field 
of  usefulness. 

Acknowledgments. 

I  wish  to  make  acknowledgments  to  Messrs.  Lazarus  White  and 
Bertrand  H.  Wait,  Division  Engineers,  in  immediate  charge  of  the 
City  Tunnel,  and  to  Mr.  J.  S.  Langthorn,  in  charge  of  the  Execu- 
tive Division  of  the  City  Aqueduct  Department,  and  to  Mr.  M.  J. 
Ungrich,  Assistant  Engineer,  and  others,  for  their  assistance  in 
compiling  the  information  contained  in  this  paper. 


94    DISCUSSION  :  PROGRESS  OF  CITY  TUNNEL  OF  0AT8K1LL  LQUBDUOT. 


DISCUSSION. 


A  Member. — On  the  first  slide  shown  of  the  pipe  lines  running 
from  Brooklyn  to  Staten  Island,  there  seemed  to  he  an  extension 
on  the  Jersey  coast,  one  coming  out  at  about  Port  Afonmouth,  or 
somewhere  there. 

Walter  K.  Speak.  M.  M.  E.  N.  Y. — We  are  not  invading  \.\\ 
Jersey.  The  conduit  leaving  Shaft  23  goes  through  Third  Avenue, 
Park  Place,  Fifth  and  Sixth  Avenues,  to  Bay  Ridge,  and  crosses 
the  Narrow-  a  I  Seventy-ninth  Street,  to  the  foot  of  Arrietta  Street 
on  Staten  Island,  and  from  that  point  passes  in  the  most  direct  route 
up  to  Silver  Lake,  where  the  proposed  Reservoir  is  to  be  constructed. 
That  is  the  end  of  that  conduit.  The  other  conduit,  leaving  the 
tunnel  at  Shaft  24  at  Fort  Greene  Park,  is  to  be  laid  through 
Willoughby  Avenue  to  Queens  Borough,  and  ends  at  Thompson 
Avenue.    Those  are  the  only  conduits  we  propose  to  build. 

Sidney  W.  Hoag,  Jr.,  M.  M.  E.  N.  Y. — Mr.  Spear,  what  do  you 
mean  by  the  terms  waterway  -hafts  and  section  valve  shafts  1  What 
is  the  distinction  between  such  shafts  and  others  % 

Mr.  Spear. — The  waterway  shafts  of  the  City  Tunnel  are  those 
through  which  water  will  be  drawn  from  the  tunnel  for  the  supply 
of  the  City. 

Only  one  of  the  shafts  of  the  City  Tunnel — Shaft  No.  1 — is  a 
construction  shaft  similar  to  most  of  those  in  the  other  pressure 
tunnels  of  the  Catskill  Aqueduct  which  are  filled  in  and  plugged 
when  the  tunnel  is  finished.  One  other  shaft — Xo.  11 — is  a  drain- 
age shaft,  without  a  waterway,  so  that  twenty-two  out  of  the  twenty- 
four  shafts  are  waterway  shafts  and  have  one  or  more  riser  pipes 
in  them  connecting  with  the  distribution  mains. 

A  section  valve  will  be  placed  across  the  tunnel  at  Shafts  13 
and  18,  which  will  serve  to  cut  off  the  portion  of  the  tunnel  on 
either  side,  for  inspection  or  repairs.  These  shafts  are,  therefore, 
termed  section  valve  shafts. 

Mr.  Hoag. — What  is  the  grade  of  the  flow  line  across  the  X ar- 
rows from  Brooklyn  to  Staten  Island? 

Mr.  Spear. — With  a  flow  of  250  million  gallons  per  day  in  the 
City  Tunnel  and  a  delivery  of  10  million  gallons  per  day  to  Staten 
Island,  the  gradient  in  the  36-in.  pipe  across  the  Narrows  will  be 
about  Elevation  260  above  sea  level.  With  the  full  flow  of  500 
million  gallons  per  day  through  the  City  Tunnel,  the  gradient  in 
the  Narrows  will  be  about  Elevation  230. 

Mr.  Hoag. — You  propose  to  lay  the  36-in.  pipe  across  the  Nar- 
rows in  a  dredged  trench? 

Mr.  Spear. — Yes,  in  a  dredged  channel;  and  the  pipe  will  prob- 
ably be  laid  from  a  cradle  supported  on  one  or  more  scows,  much  the 


DISCUSSION  :  PROGRESS  OF  CITY  TUNNEL  OF  CATSKILL  AQUEDUCT.  95 


same  as  a  pipe  of  the  same  size  was  laid  across  the  Harlem  River 
some  time  ago. 

The  conduit  from  Shaft  23  is  to  be  a  66-in.  steel  pipe,  and  a 
portion  of  it  is  now  being  la.id  on  Sixth  Avenue.  From  Fifth 
Avenue  and  Thirty-sixth  Street  to  Silver  Lake,  with  the  exception 
of  that  section  in  the  Narrows,  48-in.  cast-iron  pipe  will  be  laid. 
The  first  section  of  the  conduit  from  Shaft  24  to  Queens  Borough 
is  also  to  be  a  06-in.  steel  pipe  as  far  as  Willoughby  Avenue  and 
Broadway,  and  a  48-in.  cast-iron  pipe  the  remainder  of  its  length. 
Three  out  of  the  four  contracts  in  Brooklyn  and  Queens  Boroughs 
are  now  under  way. 

Samuel  C.  Thompson,  M.  M.  E.  X.  Y. — Is  it  intended,  Mr. 
Spear,  that  the  entire  pressure  from  the  tunnel  will  enter  into  the 
distribution  i 

Mr.  Spear. — In  the  low-pressure  districts  there  will  be  regulating 
valves  in  these  chambers  at  the  top  of  the  shafts,  by  which  any 
desired  pressure  may  be  maintained  on  the  distribution  side.  In 
the  high-pressure  districts  of  Manhattan,  Brooklyn  and  Richmond 
it  will  not,  of  course,  be  necessary  to  make  such  reductions  in 
pressure. 

Mr.  Hoag. — Then,  Mr.  Spear,  the  idea  is,  by  this  system  to 
deliver  water  direct  from  the  Catskills  into  the  houses,  without 
the  intervention  of  receiving  or  distributing  reservoir-? 

Mr.  Spear. — That  is  true,  except  for  Hill  View  Reservoir  in 
Yonkers,  just  beyond  the  City  line,  and  the  terminal  reservoir  in 
Staten  Island. 

Mr.  Hoag. — Will  the  Hill  View  Reservoir  be  a  part  of  this  sys- 
tem?   Will  the  head  there  control  the  pressure? 

Mr.  Spear. — Yes,  the  head  there  will  control  the  pressure  in  the 
City  Tunnel. 

William  F.  Laase,  M.  M.  E.  N.  Y. — Mr.  Chairman,  I  would  like 
to  ask  Mr.  Spear  what  would  happen  if  the  valve  at  the  foot  of  the 
riser  should  get  out  of  order?  What  provision  has  been  made  for 
repairing  it,  or  how  long  a  time  it  would  take  if  serious  accident 
happened  to  it? 

Mr.  Spear. — Xone  of  these  valves  have  yet  been  purchased  or 
delivered,  but  I  understand  that  they  are  of  the  simplest  design 
and  the  likelihood  of  their  getting  out  of  order  is  exceedingly  small. 
Should  it  be  impossible  at  any  time  to  open  or  close  one  of  these 
valves  when  desired,  there  would  be  nothing  else  to  do  but  to  close 
off  the  nearest  section  valve  and  pump  the  water  out  of  the  tunnel. 
We  believe  that  this  will  seldom  be  necessary,  because  these  riser 
valves  are  to  be  used  only  in  an  emergency,  and  will  therefore  not 
be  operated  frequently.    There  are  two  valves  on  each  connection 


9G   DISCUSSION  :  PROGRESS  of  city  tunnel  of  CATSKILL  A.QUBDUOT. 


a1  the  top  of  the  shaft,  one  of  which  is  to  be  a  service  valve  and 
the  second  which  is  kept  in  reserve  and  on  whieh  very  little  WQ&T, 
of  course,  can  take  place. 

Mk.  EOAO. — Is  there  anything,  M  r.  Spear,  in  connection  with 
this  Oity  Tunnel  system  t hat  prohibits  its  becoming  a  part  of  the 
present  distribution  system  in  Manhattan! 

Mr.  Spkar. — The  gradients  in  a  large  part  of  the  present  dis- 
tribution system  of  Manhattan  are  too  low  to  permit  of  the  City 
Tunnel  becoming  part  of  this  system,  in  so  far  as  a  flow  may 
under  present  conditions  take  place  in  either  direction  between 
the  tunnel  and  the  distribution  system.  If  it  were  desired  to  do 
so,  however,  the  tunnel  could  in  part  be  operated  at  a  lower  gradient 
than  now  proposed  by  closing  off  one  of  the  section  valves  and 
using  a  portion,  say  between  Shafts  13  and  18  or  that  portion 
between  18  and  the  Brooklyn  shafts,  as  a  part  of  the  distribution 
system. 

Lazarus  White,  M.  M.  E.  N.  Y. — As  I  understand  the  paper,  it 
was  primarily  a  progress  report.  It  was  not  intended  to  be  a  full 
exposition  of  why  the  Oity  Aqueduct  tunnel  was  built;  that  was 
pretty  thoroughly  gone  into  for  a  period  of  three  or  four  years  and 
the  project  won  out  handsomely. 

When  we  started  work  on  the  Catskill  Aqueduct,  it  appeared 
that  the  pressure  tunnel  would  be  an  exceptional  feature  of  the 
aqueduct.  As  the  pressure  tunnels  were  built  they  began  to  grow 
more  in  favor  and  they  won  out  up  the  State  where  deep  valleys 
had  to  be  crossed.  It  finally  dawned  on  the  engineers  that  it  would 
be  a  mighty  good  thing  in  the  city  to  distribute  the  Catskill  supply 
by  pressure  tunnels  and  to  avoid  the  trouble  of  constructing  sur- 
face pipes.  The  project  was  such  a  large  one  that  it  naturally  met 
with  opposition.  We  are  now  far  enough  advanced  to  know  that 
the  difficulties  which  the  opposition  raised  were  largely  imaginary. 
There  has  been  no  special  difficulty  in  sinking  the  shafts  or  driving 
the  tunnels  in  the  City;  we  have  found  that  the  deeper  we  go  the 
better  we  find  the  rock,  and  the  rocks  which  we  found  treacherous 
in  Manhattan  at  60  ft.  are  much  better  at  200  ft.  Except  in  a  few 
instances  the  tunnels  are  remarkably  dry.  As  for  the  quality  of 
the  rock  in  the  tunnel  we  know  now  that  these  tunnels  will  not  be 
difficult  to  construct,  and  we  believe  that  we  have  done  the  hardest 
work  in  getting  down  to  rock  through  the  cover  of  sands  and 
gravels. 

It  would  appear  to  me  that,  in  the  future,  deep  tunnels  will  be 
resorted,  to  for  other  purposes  besides  delivering  water.  Instead 
of  periodically  ripping  up  the  streets,  it  seems  that  tunnels  dis- 
tributing gas  and  electricity  might  be  built.    Considering  the  amount 


discussion:  progress  of  city  tunxel  of  catskill  aqueduct.  97 

of  work  we  are  doing,  I  think  anybody  will  admit  the  disturbance 
at  the  surface  is  very  small.  The  shafts  are  inconspicuous,  and, 
except  for  a  few  of  our  neighbors,  only  a  few  are  being  disturbed. 

The  average  progress  of  sinking  the  shafts  in  the  City  will 
probably  average  higher  than  on  our  other  tunnels,  although  the 
individual  records  will  not  be  as  high.  The  tunnels  will  probably 
be  constructed  at  a  rate  not  as  high,  relatively,  as  the  shaft  sinking, 
due  to  the  unfavorable  conditions  of  working  in  the  City  and  the 
character  of  the  rock  structure. 

Mr.  Ho ag. — What  is  the  relative  cost  per  linear  foot  between 
shaft  and  tunnel? 

Mr.  White. — It  is  hard  to  state  from  the  contractors'  prices, 
since  the  contractors  have  a  tendency  to  bid  a  little  high  on  the 
shafts  to  pay  for  the  first  expenditure  on  plant  and  equipment. 
About  two  to  one  is  probably  the  actual  relative  cost. 

Mr.  Hoag. — Is  not  the  fact  that  there  has  been  so  little  water 
in  the  shafts  and  tunnels  somewhat  of  a  revelation?  Was  that 
anticipated  by  the  geologist? 

Mr.  White. — I  believe  the  amount  of  water  has  been  less  than 
could  reasonably  be  expected.  Some  of  the  shafts  have  been  almost 
bone  dry. 

Bertrand  H.  Wait,  M.  M.  E.  X.  Y. — I  have  nothing  of  interest 
to  add  to  Mr.  Spear's  paper,  unless  it  might  be  a  few  words  in 
regard  to  some  of  the  details  which  affected  progress  on  the  City 
shafts  up  to  date. 

Previous  to  starting  work  on  the  Catskill  system,  the  shafts 
which  had  been  sunk  in  Xew  York  State  were  very  limited,  both 
in  number  and  depth.  As  a  general  rule,  these  shafts  formed  a 
very  small  proportion  of  the  work  in  hand,  and  the  contractors 
did  not  organize  especially  for  them.  They  put  an  organization 
on  the  ground  to  take  care  of  the  major  part  of  the  work  and  let 
their  men  sink  the  shafts  as  best  they  could. 

When  the  Catskill  work  was  started,  it  was  realized  that  the 
number  of  shafts  to  be  sunk  and  their  depth  made  them  something 
of  a  problem  in  themselves.  Shaft-sinking  organizations  were 
brought  in  from  the  Pennsylvania  and  West  Virginia,  coal  regions 
by  the  different  contractors.  These  men  were  all  experienced  when 
they  first  came  on  the  Catskill  work;  they  sank  shafts  on  the  dif- 
ferent contracts  all  the  way  from  Ashokan  to  the  City  and  became 
more  expert  as  they  got  accustomed  to  the  different  rocks  encountered 
in  this  part  of  the  country.  The  result  was  that  the  City  Tunnel 
reaped  the  benefit,  as  we  were  able  to  get  the  best  of  the  gangs 
which  had  been  working  along  the  line.  It  was  due  to  these  organi- 
zations that  most  of  the  good  progress  has  been  made  here. 


98    DISCUSSION  :  PROGRESS  OF  CITY  TUNNEL  OF  OATSKILL  AQUEDUCT. 


Another  thing  which  helped  out  progress  on  the  City  Tunnels 
was  the  faet  that  most  of  the  shafts  were  circular  in  section.  In 
these  circular  shafts  it  is  possible  to  do  all  the  drilling  for  a.  round 
on  one  shift,  mucking  the  other  two  shifts,  and  in  this  way  getting 
one  round  out  of  the  shaft  each  24  hours.  This  works  out  well 
both  for  speed  and  cost.  All  the  drillers  can  be  carried  on  one 
shift  and  each  day  the  drillers  and  muckers  have  a  definite  task  be- 
fore them.  The  rock  also  stands  up  much  better  in  circular  shafts 
than  in  the  rectangular  ones,  and  it  is  possible  to  sink  safely  to 
greater  depths  before  following  up  with  concrete  lining. 

A  method  of  sinking  followed  to  a  considerable  extent  on  the 
City  Tunnels,  which  was  not  tried  out  in  this  part  of  t he  country 
previously,  was  the  use  of  small  hammer  or  jap  drills.  Several 
types  of  jap  drills  were  tried  out,  but  the  best  progress  was  made 
with  the  Ingersoll  rotating  drills.  These  drills  weigh  about  90 
pounds  each  and  can  be  handled  by  one  man.  They  require  no 
tripods,  and  only  one  helper  to  every  four  or  five  drill  runners. 
In  ordinary  rock,  holes  to  a  depth  of  10  ft.  can  be  drilled  as 
fast  as  with  the  ordinary  slugger  drills.  On  account  of  having 
no  tripods  or  heavy  drills  to  get  into  the  hole,  the  shifts  can  get  in 
so  much  quicker  than  when  they  have  the  big  drills  to  handle. 
When  the  drilling  is  finished  they  can  also  pick  up  and  get  out  of 
the  hole  in  a  shorter  time. 

Conditions  were  not  as  favorable  for  speed  in  the  City  as  up 
the  State,  where  the  shafts  were  outside  of  city  limits  and  where 
the  blasting  did  not  disturb  the  residents.  There  were  some  delays 
in  getting  started,  due  to  the  fact  that  it  took  some  time  to  get  the 
necessary  permits  to  go  ahead  with  the  work.  All  that  the  con- 
tractors up  State  had  to  do  was  to  set  up  a  derrick  and  boiler  and 
start  work.  The  time  of  shooting  in  the  City  has,  in  general,  been 
kept  within  the  hours  of  7  a.  m.  and  lip.  m.,  as  it  was  found  that 
blasting  during  the  late  evening  or  early  morning  hours  disturbed 
the  residents  in  the  vicinity  of  the  shafts.  Another  thing  which 
caused  some  delay  was  the  problem  of  getting  muck  away  from  the 
shafts.  In  only  a  few  cases  was  it  possible  to  spoil  near  the  shafts ; 
it  all  had  to  be  hauled  a  considerable  distance  by  teams  or  motor 
trucks. 

Taking  everything  into  consideration,  the  general  progress  on 
these  shafts  to  date  has  been  better  than  could  be  expected.  This 
has  been  due  primarily  to  the  superior  organization  of  the  con- 
tractors and  the  good  quality  of  the  rock  encountered.  The  most 
notable  advance  in  methods  that  has  been  developed  on  the  City 
Tunnel  has  been  the  use  of  jap  drills  in  sinking. 


discussion:  progress  of  city  tunnel  of  catskill  aqueduct.  99 

Herbert  M.  Hale." — I  would  like  to  say  that,  of  course,  in  start- 
ing work  in  the  City  of  the  magnitude  of  the  City  Tunnel,  the 
problem  of  our  relations  to  the  several  departments  of  the  City 
government  was  an  important  one.  The  contractors  have,  without 
exception,  found  that  the  City  departments  are  well  organized,  and 
contractors  have  been  very  well  treated  by  everybody  concerned. 
Of  course,  the  Board  of  Water  Supply  could  not  buy  all  the  private 
property  at  the  site  of  the  City  Tunnel  shafts  which  was  necessary 
to  carry  on  this  work,  but  the  other  departments  came  to  the  rescue 
and  allowed  us  to  bridge  streets  and  encroach  a  little  on  the  high- 
ways and  parks.  With  all  the  restrictions  placed  by  the  City  on  our 
operations,  there  was  one  thing  the  City  department  did  not  do — 
they  did  not  set  any  limit  as  to  how  high  we  could  go  above  the 
ground  with  our  plant.  In  many  cases  by  building  several  decks, 
as  at  Shaft  19,  we  have  thereby  more  than  doubled  the  working  areas. 

Mr.  Spear. — I  want  to  add  a  little  more  about  this  question  of 
permits.  The  Board  of  Water  Supply  have  not  the  broad  powers 
which  the  old  Rapid  Transit  Commission  had — to  go  anywhere 
they  chose — and  we  have  had  to  make  application  to  the  depart- 
ments having  jurisdiction  over  City  lands  for  permission  to  occupy 
them,  and  the  contractors  have  had  to  go  to  them  for  many  per- 
mits for  carrying  on  their  work.  I  want  to  state  that  we  have 
been  very  well  treated  by  the  other  City  departments.  Further- 
more, I  want  to  say  that  if  there  has  been  any  delay  in  securing 
permits  it  has  been  due  to  the  contractors  who  came  in  here  with- 
out knowledge  of  the  City  departments,  and  who  did  not  at  first 
know  just  where  to  go  to  get  the  permission  they  sought. 

Mr.  Hoag. — It  does  seem  that,  for  work  of  this  magnitude  and 
importance,  it  is  being  conducted  with  far  less  fuss  and  feathers, 
as  far  as  the  lay  observer  can  see,  than  has  characterized  any  great 
public  or  municipal  improvement  heretofore.  I  mean  by  the  "lay 
observer,"  those  outside  of  the  Board  of  Water  Supply,  and  I  think 
it  is  due  largely  to  the  co-operation  of  the  various  departments  in 
lending  their  aid  and  assistance  on  lines  of  least  resistance. 

William  F.  Laase,  M.  M.  E.  N.  Y—  I  have  been  led  to  believe 
that  a  daily  supply  of  about  200  000  000  gal.  will  be  available  in 
Brooklyn  by  the  end  of  1915,  and  I  would  like  to  ask  if  the  rate 
of  progress  on  the  work  confirms  that  belief? 

Mr.  Spear. — Yes.  Contract  No.  67,  the  last  contract  in  lower 
Manhattan  and  Brooklyn,  is  the  one  which  will  take  longest  to 
complete.  That  is  to  be  completed  in  December,  1915,  and,  at  the 
present  time,  the  contractors  are  ahead  of  their  schedule. 


^Engineer  with  Holbrook,  Cabot  and  Rollins  Corpoiation,  Contract  67  of  City  Tunnel. 


I 


